Variable-speed drive



L. S. HOBBS ETAL VARIABLE SPEED DR IVE May 14,1946.

Filed June 26, 1943 3 Sheets-Sheet 1 INVENTORS Leonard $.H0bbs ndre WVDWIIZ ATTOR N EY.

I May 14,1946. L. s. HOBBS ETAL 2,400,307

VARIABLE SPEED DRIVE I Filed June 26, 1943 3 Sheets-Sheet v INVENTORS l e on al'd 8.3011115 zzdrewknmllyoog ATTORNEY L. s. HOBBS EIAL 2,400,307

VARIABLE SPEED DRIVE May 14, 19 46.

s Sheets-Sheet 3 Filed June 26; 1943 INVENTOR Leonard S. Hobbs Andrew VD. W'z'llyoos BY ATTORNEY.

Patented May 14, 1946 UNITED .s'rArEs PATENT OFFICE I v vamp i le DRIVE i Leonard S. Hobbs and Andrew V. D. w lo l,

. West Hartford, Conn assignors to UnitedAircraft Corporation. Elli poration-oi Dela-ware Hartford, Com, a cor- Application June 2c, 1943, serial No. 492,423

18Claims.i(CL 123-.-119)-- v I blowers may be provided, with my improved drive This invention relates to an improved variable speed drive. particularly adapted for driving an internal combustion engine blower, such as a supercharger or an engine cooling fan.

Reference is made to the co-pending application. Serial No. 492,422, filed June 26, 1943. concurrently herewith, by Leonard S. Hobbs,-assigned to the applicants, assignee, which relates to an invention of which the present invention is a modification or improvement.

An object of this invention is to provide an improved hydraulic transmission having a variable speed ratio in which the efficiency of the drive will be high throughout the range of transmission speed ratios.

Other objects and advantages will be apparent from the specification and claims, andfrom the accompanying drawings which illustrate what is now considered to be apreferred embodiment of the invention.

In the drawings,

Fig. 1 is a schematic view of an internal combustion engine provided with a two-stage supercharger, one stage of which is driven by the variable speed drive of this invention.

Fig. 2 is a detail view. partly in section, of

applied toany or all oi said stages.

The first stage of the supercharger is driven through a speed increasing gear train 32- by engine crankshaft 341 The second stage is driven by shaft 36 connected with the first stage and driving the second stageimpeller through a low speed range by a low speed gear train including a fluid coupling 44. and through a high speed range by -a high speed gear train including a fluid coupling 42. While the drawings show only one coupling'in each gear ratio, it will be underthe variable speed drive of Fig. l.

Fig. 3 is a sectional view of the valve port lfloi Fi 1.

Fig. 4 is a sectional view of the valve port I40 of Fi 1.

Fig. 5 is a diagrammatic view of a three speed ratio transmission, showing in sectiona modification of the valve of Fig. l as adapted for use with a three-speed drive.

Fig. 6 is a.view along the line 6-6 of Fig. 2.

Fig. 7 is a view similar to Fig. 6 but showing the, ring valve in closed position.

Figs. 8 and 9 are sectional views showing the ring valves of the two lower speed ratio couplings of Fig. 5. v

In the embodiment shown in the drawings, an engine l0 having a cylinder. I2 is supplied with intake air through induction pipes, one of which is shown at i4. A supercharger comprising main blower stage It and auxiliary blower stage It takes air from inlet 20 and initially compresses stood by those skilled in the art .that additional couplings may bearranged in parallel in any one gear ratio if necessary to transmitthe required torque. 'Additional gear ratios may also be provided if desired, to give additional ranges of blower speeds. I

The driving members or impellers of couplings 4! and 42 are each driven by gear 44 on shaft 38 and the meshing gears 46 and 52, respectively, while the .driven member or runner of coupling 4. is connected through a low speed gear drive 48, 50 to the impeller 22 andthe driven member or runner of coupling 42 is connected to the impeller 22 through a high speed gear drive 54, 56.

Couplings or clutches 40 and 42 are ofthe type wherein the slip between the driving and driven members thereof is -dependent upon the amount of fluid present in the working chamber and the efflciency' of the coupling is a function of the slip, becoming higher as the amount of slip becomes lower. These couplings are provided with restricted exit holes or drains 116 ,(Fig.

2) and the total amount of working fluid present at any one time in the coupling; and con;

sequently the slip of the coupling and the speed of the impeller driven-thereby, is altered by vary-' ing the amount of fluid supplied in. relation to the flow capacity of the drains. For sup lying fluid to t e couplings, lines 60 and 62 respec v tively co act the low-speed coupling 40 and the high-speed coupling 42 with a valve 64, which may be operated manually or automatically to it by rapid rotation of impeller vanes 24. The

air then passes through conduit 2 to vanes 20 that a greater or lesser number'of stages or admit the working fluid, such-as engine oil. to the couplings from a source or sources I 36, I38 or oil under pressure.

Valve 04 is shown as automatically'controlled I by the outlet pressure of the auxiliary blower in such manner as to maintain the blower outlet pressure substantially constant. Fluid under pressure from the conduit 28 is applied to a flexible bellows I2 through a conduit lll. Bellows I2 works against an evacuated companion bellows I4 which is fixed at It and contains spring 15. A common head member I8 is positioned between bellows I2 and I4 and will be. moved in one or the other directionby variations in the fluid pressure applied to bellows I2 thro fi con duit I0. An increase in the said pressure will move lever 82 in a clockwise direction about a fulcrum 86 by means of a link 80 pivoted at one end to the lever and at the other'end to arm 8| attached to the head I8: and a decrease in the blower outlet pressure will enable the spring 18 in the evacuated bellows 14 to move head I8 to to the stem, biases valve I in one direction and cooperates with spring I to hold'valve I00 in a central or closed position at full "throttle and for a given position of fulcrum 86 when the pressure in bellows I2 is at a predetermined value.

Valve I00 upon movement thereof in one or the other direction in response to an increase or decrease in the pressure in conduit 26 admits a fluid under pressure (such as engine lubricating oil) from source H8 to one or the other side of plunger I30 of valve 64 through conduits I22 and I24. When fluid from source I I8 is being applied to one side of plunger I30 through one of the conduits. I22, I24, then the other side of the plunger will be drained through the other of conduits I22, I24; and one of the drain ports H6, I20. These drain ports may be made restricted, if desired.

Lands or seats H0, H2, H4 of valve I00 cooperate respectively with parts H6, H8 and I to admit pressure from source I I8 to one or the other of lines I22, I24, depending upon the direction of movement of the valve, and also to close one or the other of drains H6 and I20. Thus, valve I 00 operates to mpve valve plunger I ofvalve 64 by changing the relative pressures in conduitsI2-2, I24. As valve plunger I30 is shifted to the right, port I38 leading to the low speed coupling will be first placed in communication with the supply port I36 and then, upon a further movement of plunger I30, the port I40 leading to the high speed coupling wil1 be placed in communication with supply port I39. As is shown in Figs. 3 and 4, the ports I38, I40 may be shaped to provide a desired rate of oil flow to the respective couplings at each position of the valve plunger I30.

For manual operation of the engine, throttle I is provided. This throttle is manually opened or closed to regulate the pressure in intake pipes l4, and consequently engine power, by an arm I52 1 pivotally connected to a bushing I54 slidable on throttle rod I56.

Bushing I54 and throttle rod I56 are ordinarily held against relative movement by a flange or stop I fixed to the rod and against which the bushing is held by spring I58 acting between the bushing and a disc I60 fixed to the throttle rod. After the throttle is opened .to its full extent, arm I52 contacts a stop I62 and additional force exerted on the throttle rod I56 will compress spring I58 and allow a further movement of rod I56 beyond the fully opened throttle position. An arm I64 is so positioned on rod I56 as to engage pin 88, slidably mountd in afixed support 90, simultaneously with the.en

gagement of throttle arm I52 and stop I62. The additional movement of rod I56 beyond full throttle position, as permitted by compression of spring I58, causes arm I64 to move pin 88 and the fulcrum end 86 of lever 82 to the right against the action'of spring 92 positioned'between the end of the lever and a lever stop and spring guide pin -94 attached to a fixed support 96.

The position of fulcrum 86 may be so selected that for part throttle conditions, when'arm I64 is separated from pin 88 and fulcrum 86 is held in the extreme lefthand position by spring 92, the spring I06 will maintain valve I00 in a lefthand 10 position in which it admits oil to line I24 and thus causes valve 64 to close both coupling supply ports I38, I40. A slight shift of fulcrum 86 to the right,

' by movement of rod I66 beyond full throttle position, will shift valve I00 and bias springs I06, I5 l5 toan operative position in which the valve I00 win be operated in response to variations in fluid pressure in conduit 26 and bellows I2 and will control valve plunger I30 to regulate said pressure to a predetermined value. fulcrum 86 to the right, as caused by further movement of rod I56 and permitted'by compression of spring 92, will reset or adjust the control device so as to regulate thepressure in conduit 26 to higher values up to a maximum determined by the stop pin 94.

When valve 64 is opened, by either automatic or manual operation of valve I00, working fluid is first admitted from the supply port I36 to the low speed coupling- 40 and upon a further movement of plunger I30 is admitted from supply port I39 to the high speed coupling 42. The working fluid is preferably engine lubricating oil delivered under pressure to ports I36, I39 by a pump supplied from an oil sump or reservoir. The oil 88 passes from port I36 through the valve and conduit 60 to the low speed coupling by way of Ports I'I0,-I'I2, and I14 (Fig. 2) and is drained from the coupling back to the oil sump through the drain hole "6 (Fig. 2). If the low speed 40 coupling, opreating at its minimum slip, does not Upon movement of plunger I30 beyond this range,

as would be occasioned by an engine or requirement beyond that which could be supplied atthe proper pressure by the low speed gear-ratio at minimum coupling slip, port I 40 will also be uncovered and valve 64 wli1 supply oil to both conduits 60 and 62, and the high-speed coupling 42 will gradually pick up the load and drive the blower impeller through the' high gear-ratio as the port I40 is gradually opened by valve 64.

When the drive is in the high speed ratio through the coupling 42, someprovision must be made to empty the low speed coupling of oil. Otherwise, a power loss would be occasioned by the fact that the high speed coupling, when driving the blower impeller, also drives the runner of the low speed coupling through the gears 48 and 50. In other words, the driving and driven members of both couplings are always respectively interconnected by the gears 44, 46, 52 and the gears .54, 56, 50, 48 and ifsome provision were not made t empty one coupling when the other coupling was driving, then there would always be a loss of power through turbulence created in theiluid in the non-driving coupling. Further, such an attempt to drive the impeller through diiierent Further movement of Fig. 2'shows a very eifective arrangement for cutting on thesupply of oil to the low speed coupling as'the high speed coupling takes over .the load. A bushing or ring valve I80 encircles the shaft I8I upon which the driving element I83 and the driven element I85 01' the coupling revalve. This ring valve has a frictional running fit I8I with the. driving element I83 and has a free fit and a lost-motion pin and aslot connection I88, I84 with the driven element I85. When the low speed coupling is driving the blower, the runner I85 of the coupling will always be turning slower than the impeller I83 and valve I80 will be held by the runner with the pin I88 against one side ofthe slot I84 (depending upon the direction of rotation of the coupling) as is shown in Fig. 6. Thus, the ring valve will be positively connected to runner I88 through pin I88 but will tend to turn with impeller I83 because of the frictional fit between the mating surfaces I8I of the valve and the coupling impeller. The tendency of the ring valve I80 to turn with the driver I83 of the coupling is greatly increased by the provision of drain ports I19, which relieve the oil pressure on one side of the ring and enable the oil pressure within the ring toiorce the ring hard against the driver I83, creating considerable friction for movement of the ring with the driver. Thus, the ring'valve I80 is forced by oil pressure, as in the manner of a piston, into frictional enthe coupling, then runner I85 will be rotated slower than impeller'l83 and valve I80 will be returned to the open position in which it supplies oil to coupling 40. The oil supply to coupling 42 may be admitted through a hollow countershaft in a manner similar to the mode of oil admission hown in the drawings for coupling 40, but with the ring valve I80 omitted.

In operation, if the pressure in conduit 28 drops below a predetermined value, which value may be adjusted or modified by moving rod I58 to shift the position of fulcrum 86, val"e I00 will be moved to the right by the action of spring I8 in bellows I4. Oil under pressure from source I I8 will then create a pressure diil'erence across valve 84 and shift'plunger I30 to the right to increase the oil supply to the fluid coupling which is engaged. As the size of the drain orifice (or orifices) I18 is fixed an increase in the amount of oil supplied to the coupling will increase the amount of fluid maintained therein, and will decrease the slip of the coupling and consequently increase the speed of blower impeller'22. If the resultant increase in the speed of the blower is not suflicient to maintain the pressure in manifold'28 at the desired value, a further operation of valve I00 will further open valve 84 to admit an increased quantity of oil to the transmission; conversely, if the manifold pressure increases beyond the predetermined value, the quantity of oil admitted to the transmission -will .be decreased, until the gagement with driver I83. When impeller I83 is turning faster than runner I85, a port I82 in the valve matches with the port H4 in the runner and the oil supply is passed to the coupling through these ports and out through the drain I18. Upon an assumption of the blower load by the high speed coupling 42, the runner I85 of the low speed coupling will be turned faster than the impeller I83 by gears 58, 48 when the blower shaft 23 has begun to be rotated by the high speed coupling 42 rather than by the low speed coupling 40. As runner I88 begins rotating faster than impeller I83, pin I88 will ride over against the other side of slot I88, to the position shown in Fig. 7. Friction between ring valve I80 and the impeller I83 tends to turn these two members together but the ring valve is positively driven with runner I85 through the pin and slot connection. Thus, the ring valve will assume either the open position of Fig. 6 or the closed position of Fig. 7 in accordance with predetermined changes in the relative speed of the impeller and runner members, de-- pending (in the embodiment of the drawings) on whether or not the impeller I83 of the low' speed pressure at the desired value.

amount of oil in the driving coupling is maintained just sufflcient to hold the engine charging Thus the blower speed will be varied in response to' changes in ressure on the outlet side of the blower and the transmission will automatically shift the blower drive from one gear ratio to another depending upon the gear ratio required to turn the blower impeller at the speed called for by the control apparatus.

When the coupling 40 reaches its maximum capacity, or minimum'sllp, then a call by the bellows I2 for a higher blower speed will operate valve 88, to open the inlet I39 to line 82 and high speed coupling 42. This admission of oil to the high speed coupling will bring the driven element or'runner thereof gradually up to a speed at which it tends to rotatethe shaft 23 at the same speed at which the said shaft is rotated by the low speed coupling 40. A further slight increase in the speed of shaft 23 by high speed coupling 42 will reverse the direction of power transmission between coupling 40 and the gear on shaft 23 so that coupling 42 and gear 50 will rotate the runner I88 of coupling 40 faster than the impeller I83 thereof and operate ring valve I80 to cut ofi the supply of oil to the low speed coupling,

to drive blower shaft 23. the runner I85 will be I rotated faster than the impeller I83 and the valve will be turned relative to the runner I88 a distance equal to the width of slot I84 less the diameter of pin I88. This movement is made sufllcient (Fig. '7) to mask the port I" in the runner and cut oil the fiow of oil through ports I82, I" to thecoupling. Drain I18 is always open, so when the oil supply is cut of! by the ring valve, the coupling 40 will empty and enable the impeller and runner members thereof to be relatively rotated by gears 44 and 50 without absorbing any material amount of power. When the drive is in the high ratio and the slip of coupling 42 increases beyond a predetermined value, as would be caused, by a stoppage or a sufliciently large reduction in the supply of oil admitted to l and thus in effect remove it from the drive.

In this position, when the drive is in the high gear ratiofthe low speed coupling merely. floats on.

' and then the low speed port I38. When the slip of the high speed coupling increases to a value at which the runner I85 rotates slower than impeller I83, then valve I80 will be snapped to open position in which oil is admitted to coupling 40,

' which will then become engaged and will take- -over"'the blower drive as the port I40 is closed and coupling 42empties through its drain ports, which may be similar to those shown at I16.

In each gear ratio the speed of the blower may be infinitely varied by varying the amount of oil admitted to either coupling, valve 64 acting to open the ports I38 and I40 only to that degree necessary to drive the blower at a Speed sufficiently high to maintain the desired engine charging pressure. Thus, a very large number of speed ratios are provided. Furthermore, the drive may be made highly efiicient at any one of the said ratios because each of the couplings need be op- '.-=?:erated only over a low range of slip speeds. In

other words, the total variation in speed ratio is distributed among two couplings (in the embodiment shown in Figs. 1 and 2 of the drawings) so that each need operate only over the high 'efilciency portion of its slip speed range.

Fig. 5 shows a modification providing three transmission speed ranges or gear ratios. In this modification, as valve 64' is shifted to the right, a low speed coupling 40 and gear ratio 44, 46, 48, 50 is engaged by oil fed through line 60, then an intermediate speed coupling 42 and gear ratio 44, 52, 54, 56 is engaged by oil admitted to line 62, and finally a, high ratio coupling 43 and gearratio 44, 53, 55, 51 is engaged by oil fed through port I43 and line 63. The two lower speed couplings are provided with ring valves as shown in- Figures 8 and 9. Hence, as each successive gear ratio is engaged by valve 64', the lower ratios will be disengaged by the ring valves, and as each successive ratio is disengaged by the valve 64' (as it moves in a reverse direction, to the'left) the ring valves will operate to engage the coupling in the next lower ratio. In the modification of Fig. 5 a stem 65 is provided for operating the valve, either automatically or manually. Valve 64' may also be operatedhydraulically, in the manner disclosed in connection with Fig. 1.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

We claim:

1. In combination, an internal combustion aircraft engine, a charging blower therefor, a lower ratio gear train including a first fluid coupling for driving said blower by said engine over a first speed range relative to the speed of said engine, a higher ratio gear train including a secing one of said couplings ineffective when another of saidcouplings is driving.

3'. In a variable speed transmission, a drivin shaft, a driven shaft, a lower ratio gear train operatively connecting said driving shaft and said driven shaft, a higher ratio gear train operatively connecting said driving shaft and said driven shaft, a variable slip fluid coupling in each said gear train, each said coupling including a driving to admit a working fluid to each of said couplings. and a valve having a lost-motion connectionwith the driven member of one of said couplings and effective upon rotation of said driven member faster than its driving member to prevent admission of said working fluid to said one coupling.

4. In an automatic change speed transmission, a-driven shaft, a driving shaft, a higher speed ratio transmission mechanism operatively con-. necting said driving and driven shafts, at least one lower speed ratio transmission mechanism operatively connecting said driven and driving shafts, aivariable slip fluid coupling in each of said transmission mechanisms, means for connecting each of said couplings, in sequence, with a working fluid supply means, a valve for controlling the flow of said working fluid to said lower speed ratio coupling, and means operatively connecting said valve with both the driving and the driven sides of its respective coupling for shifting said valve in accordance with the relative speeds of the driving and driven sides of said coupling.

5. A fluid coupling comprising, a driving member, a driven member, means forming a fluid chamber for retaining a working fluid to torsionally connect said driving and driven members, means for admitting a working fluid to said chamber,- and avalve element positively connected with limited relative movement to one of said members and frictionally connected to the other 01' said members and having a valve port therein for controlling the admission of said fluid to said coupling.

6. A fluid coupling comprising, a driving memher, a driven member, means forming a fluid ond fluid coupling for driving said blower by said engine over a second speed range relative to the speed of said engine, means including an adjustable flow controlling means for admitting a working fluid first to one of said couplings and then to both of said couplings, fluid pressure responsive means for adjusting said flow controlling means in response to changes in the discharge pressure of said blower, and automatically operative valve means connected in series with said flow controlling means and one of said couplings for cutting off the supply of working fluid to said one coupling when'the other of said couplings is driving said blower.

2. In an aircraft engine, an engine driven shaft, a multiple speed ratio transmission operatively connected with'said engine driven shaft, a first variable slip coupling in one of said transmission ratios, a second variable slip coupling in another of said transmission ratios, means for selectively engaging one or both of said couplings, one of said couplings including a driving member and a driven member, and means positively connected with one of said members and frictionally connected with another oisaid members for renderchamber for retaining a working fluid to torsionally connect said driving and driven members, means for admitting a working fluid to said chamber, and a valve for controlling the admis- 'sion of said fluid to said chamber, said valve comprising an element frictionally engaged with one of said members and positively connected with relative rotary lost motion by a pin and slot connection to the other of said members, said element having a fluid passage therein.

7. A fluid coupling comprising, a hollow shaft, a driven element rotatable on said shaft, a driving element rotatable on said shaft, means formin a working fluid chamber between said elements, inlet means for admitting a working fluid from said hollow shaft to said chamber, continuously open outlet means for draining said fluid from said chamber, said outlet means being of less flow capacity than said inlet means, a rotatable valve for controlling the admission of said fluid to said chamber through said inlet means, said valve being positively secured with limited relative movement to said driven element, and impositive means tending to cause said valve to rotate with said driving element.

8. In combination, an aircraft engine, a blower,

a lower ratio gear train including a first fluid coupling for driving said blower by said engine over a, first speed range relative to the speed of said engine, a higher ratio gear train including a second fluid coupling for driving said blower by said engine over a second speed range relative to the speed of said engine, means for admitting a working fluid to each of said couplings, and means sensitive to a reversal in the direction of power transmission through one of said gear trains for disengaging said one gear train.

9, In combination, an aircraft engine, a blower, a lower ratio gear train including a first fluid coupling having driving and driven elements for driving said blower by said engine over a first speed range relative to the speed of said engine, a higher ratio gear train including a second fluid coupling having driving and driven elements for driving said blower by said engine over a second speed range relative to the speed of said engine, adjustable flow controlling means for admitting aworking fluid first to one of said couplings and then to both of said couplings, and means responsive to a reversal in the relative speed of the driving and driven elements of at least one of said couplings for en aging and disengaging said coupling.

10. In a fluid coupling having an impeller member and a runner member, said members cooperating to form a working fluid chamber, means for varying the quantity of working fluid retained in said chamber comprising a member having a valve port therein, said member being rotatable with one of said coupling members, and means for moving said member relative to said one coupling member during rotation thereof in response to a predetermined change in the relative speed of said impeller and runner members.

11. In a fluid coupling, an impeller member, a runner member, an annular recess in said impeller member, an annular recess in said runner member, an annular member having portions thereof disposed respectively in each of said recesses, cooperating valve ports in one of said coupling members and said annular member, and a lost-motion connection providing limited relative movement between said ported coupling member and said annular member.

12. The combination of claim 11, in which said annular member has a transverse wall bearing against a wall of one of said recesses, and a pressure relief drain port open to the meeting faces 7 of said walls.

13. The combination of claim 8, in which the means for disengaging said one gear train includes valve means carried by the coupling in said one gear train for controlling the admission of working fluid to said coupling.

14. In combination, an aircraft engine, a

blower, a lower ratio gear train including a first fluid coupling for driving said blower by said engine over a first speed range relative to the speed of said engine, a higher ratio gear train including a second fluid coupling for driving said blower by said engine over a second speed range relative to the speed of said engine, means for admittin a workingfluid either to a selected one of said couplings or to both of said couplings, and means including a valve sensitive to a reversal in the direction of power transmission through said selected coupling for disengaging said selected coumission through one of said gear trains for dis-' engaging said one gear train.

. 16. The combination of claim 15, in which the means for disengaging said one gear train includes a valve for preventing the admission of working fluid to one of said couplings under predetermined conditions.

' 17. In combination, an aircraft engine, a blower, a low ratio gear train including a first fluid coupling for driving said blower by said engine, anintermediate ratio gear train including a second fluid coupling for driving said blower by said engine, a high ratio gear train including a third fluid coupling for driving said blower by said engine, means for admitting a working fluid to each of said couplings, means for controlling the slip of at least one of said couplings, and means sensitive to a reversal in the direction of power transmission through said low gear train and through said intermediate gear train for disenthrough one or said fluid passages, said valve I being rotatable with one of said coupling members, and means for moving said valve relative to said one coupling member during rotation thereof in response to a predetermined change in the relative speed of said impeller and runner members.

LEONARD S. HOBBS. ANDREW V. D. WILIGOOS. 

